The gaming industry has in recent years undergone a significant expansion. Many different types of card games, keno, lotteries, roulette, and other forms of gaming have drawn attention during this expansion. Substantial efforts have been made to add variety to such games to enhance the attractiveness of the games for the players. Despite this increased variety, the most popular form of gaming continues to be centered about slot machines. They account for approximately three-fourths of the total volume of all gambling activities in the United States and their popularity seems to be increasing.
Because of the volume of slot machine gaming, numerous devices, rules and methods of have been proposed and introduced in efforts to improve the games. Video slot machines have been introduced and were initially well received, but have not replaced the mechanical displays associated with the "one arm bandits." Push button operation has also come and passed through popularity. Despite many such noticeable improvements or changes, many people still prefer the more traditional mechanical slot machines. The action and sounds of mechanical reel slot machines have a particular and very widespread appeal to a large number of gamblers seeking this form of entertainment.
Despite numerous improvements made over the years since 1892, when machines that paid off in coins were introduced, there remains a need for improved slot machines and methods which provide more attractive slot machine play and associated entertainment.